Floor grinders



April 14, 1954 A. TOSETTI 3,128,581

FLOOR GRINDERS Filed April 3, 1962 I 52 4 1 2A 60 '55 T INVENTOR A NTONIO TOSETTI United States Patent This invention relates to grinders for floors, such as terrazo, mosaic, granite and marble floors.

An object of the present invention is the provision of a floor grinder having a plurality of grinding elements,

each including one or more standard grinding stones, and each moving downwardly independently of the others as the stones wear away.

Another object is the provision of a floor grinder including a plurality of independent grinding stones all fully bearing on the floor during operation of the machine regardless of the relative wear of said stones.

A further object is the provision of a floor grinding machine so constructed that each of a plurality of grinding stones thereof may be completely used up regardless of the degree of wear of the other stones.

Yet another object is the provision of floor grinding apparatus having a driving arrangement which not only turns a plurality of independent grinding elements, but also imparts a downward component to said elements during operation of the apparatus.

With these and other objects in view the present in-. vention will now be described with reference to the accompanying drawings, in which:

FIGURE 1 is a reduced side elevation of a grinder according to this invention;

FIGURE 2 is a top plan view of this machine;

FIGURE 3 is an enlarged vertical section taken on the line 33 of FIGURE 1, illustrating a preferred driving arrangement for the grinding elements;

FIGURE 4 is a horizontal section taken on the line 4-4 of FIGURE 3;

FIGURE 5 is an enlarged bottom plan view of a grinding element or holder; and

FIGURE 6 is a view similar to FIGURE 3, illustrating an alternative driving arrangement.

Referring to FIGURES 1 and 2 of the drawings, 10 is a floor grinding machine including a suitable carriage 12 carrying or supporting a grinder 14. In this example, carriage 12 has a pair of wheels 18 at the back end thereof and a single wheel 19 at its forward end midway between the sides thereof. Suitable supporting means, such as a pair of arms 23, project forwardly from the carriage and carry the grinder 14.

Grinder 14 includes a cylindrical casing 27 carried by arms 23 of carriage 12. Suitable power means, such as an electric motor 29, is suitably mounted on the top of casing 27.

FIGURES 3 and 4 illustrate a preferred driving arrangement for grinding elements of grinder 14. In this example, casing 27 is provided with a bottom 32 and a horizontal support or wall 33 spaced upwardly from said bottom but below the top 34 of the casing. One or more vertical shafts 38, in this example there are three of these shafts, are each mounted for vertical and rotary movement in bearings 40 and 41 in bottom 32 and support 33, respectively. A standard holder 44 is fixedly secured to the lower end of each shaft 38. Each holder has the usual intersecting slots 45 and 46 opening downwardly therefrom into which one or more standard grinding stones 48 removably fit. These stones may be of any size, but the standard stone is usually about 2 inches by 2 inches by 8 inches. Different arrangements of the stones may be used in holder slots 45 and 46. For example, one whole stone may be inserted in slot 45 and two lengths of stone inserted in slot 46 on the opposite sides of slot 45, or a length of stone may be inserted in the portions of each of the slots extending away from the centre of the holder. FIGURE 5 shows a full stone 48 in slot 45 and lengths of a stone in slot 46.

Motor 29 has a drive shaft 50 extending downwardly therefrom through bearings 51, 52 and 53 in casing top 34, support 33 and bottom 32 centrally of casing 27. A central gear 55 is fixedly mounted on shaft 50 between bottom 32 and support 33. This gear is relatively wide, as clearly shown in FIGURE 3, and it is formed with teeth 57 that are inclined relative to the axis of the gear and shaft 50. Each shaft 38 has a relatively narrow lateral gear 60 fixedly mounted thereon and meshing with central gear 55. Each lateral gear 60 has teeth 62 which are inclined to correspond with the inclination of central gear teeth 57. If desired, casing 27 may be filled with heavy oil or grease.

When motor 29 is operating, central gear 55 is rotated by shaft 50. This in turn rotates the lateral gears 66), shafts 38 and the grinder elements at the lower ends of said shafts formed by holders 44 and stones 48. When machine 10 is in operation, the grinding stones 48 rest on the floor and keep shafts 38 and their respective gears 60 in proper position within the machine. As the stones wear away, shafts 38 and gears 60 move downwardly, said gears meshing with the central gear 55 at all times. Thus, the stone or stones of each holder wear away independently of those of the other holders so that each stone mantains full contact with the floor regardless of the wear thereof relative to the wear of the other stones. The stones of each holder 44 may be worn down as far as possible regardless of whether the stones of the other holders are new and/or partially worn down. Thus, the individual grinding elements of the shafts 38 move downwardly independently of each other. An important feature of this invention is that the inclination of teeth 57 and teeth 62 of the central and lateral gears impart a downward component to said lateral gears, shafts 38 and holders 44 with their stones 48. The incline of the teeth is such that the central gear maintains a downward pressure on the lateral gears during the operation of the machine. This results in a downward pressure on the grinding stones making for more even and quicker grinding of the floor.

If desired, a small machine may be made with only one grinding element. This would function in the same manner as the machine described above. The central gear would impart a downward component to said grinding element, and the latter would move downwardly as the grinding stone wore away.

FIGURE 6 illustrates an alternative driving arrangement for shafts 33, holders 44 and stones 48. In this example, the bottom 32 and support 33 of casing 27 are omitted. A central gear 78 is fixedly secured to top 34 within and centrally of casing 27. The motor shaft 50 extends through but is not connected to gear 70 and carries at its lower end a lower support 72 that is rotatable in casing 27 near the lower end thereof. An upper support 73 is located above support 72 and connected thereto to rotate therewith by a large collar 75. Upper support 72 has a large central hole 76 therein so that said support surrounds but clears central gear 70. Each vertical shaft 33 is mounted in bearings 78 and 79 carried by supports 72 and 73, and is rotatable and vertically movable in said bearings.

The alternative machine of FIGURE 6 operates in the same manner as the machine described above, excepting that instead of motor shaft 5t) rotating central gear 70, it rotates supports 72 and 73 which, in turn, move shafts 38 circumferentially around said central gear. As lateral gears of) mesh with gear '78, they rotate at this time and consequently rotate shafts 38, holders 44 and stones 48. Thus, the stones not only rotate around the vertical axes of shafts 33, but they move circumferentially around the common axis of gear 79 and shaft 50. If desired, this alternative may have only one shaft 38 and the elements associated therewith.

What I claim as my invention is:

1. In a machine for grinding floors, a central gear having teeth inclined in an axial dlection, a plurality of floating vertical shafts arranged around and radially spaced from said central gear and mounted for rotary movement, a lateral gear having correspondingly inclined teeth fixedly mounted on each shaft and meshing with the central gear, said shafts and their respective lateral gears being free at all times during operation to move up and down, a grinding element mounted on a lower end of each vertical shaft and supporting the latter shaft and the lateral gear mounted thereon, and driving means for causing the vertical shafts and the grinding elements thereof to rotate, the incline of the teeth of the central and lateral gears being such as to impart under the action of said driving means a downward component to the lateral gears, shafts and grinding elements during rotation of said shafts.

2. A machine as claimed in claim 1 in which the central gear is Wide enough to permit each lateral gear to move downwardly While continuing to mesh therewith a predetermined distance as the grinding element associated with each lateral gear wears away.

3. In a machine for grinding floors, a central gem having teeth inclined in an axial direction, a plurality of floating vertical shafts arranged around and radially spaced from said central gear and mounted for rotary movement, a lateral gear having correspondingly inclined teeth fixedly mounted on each shaft and meshing with the central gear, said shafts and their respective lateral gears being free at all times during operation to move up and down, a holder mounted on a lower end of each vertical shaft and adapted removably to hold a grinding stone projecting downwardly therefrom, said grinding stone supporting its holder, shaft and the lateral gear mounted on the latter, and driving means for causing the vertical shafts and holders to rotate, the incline of the teeth of the central and lateral gears being such as to impart under the action of said driving means a downward component to the lateral gears, shafts and holders during rotation of said shafts.

4. In a machine for grinding floors, a central gear having teeth inclined in an axial direction, a plurality of floating vertical shafts arranged around and radially spaced from said central gear and mounted for rotary movement, a lateral gear having correspondingly inclined teeth fixedly mounted on each shaft and meshing with the central gear, said shafts and their respective lateral gears being free at all times during operation to move up and down, a grinding element mounted on a lower end of each vertical shaft and supporting the latter shaft and the lateral gear mounted thereon, and power means connected to the central gear to rotate the latter gear and thereby rotate the lateral gears, vertical shafts and grinding elements, the incline of the teeth of the central and lateral gears being such as to impart under the action of said driving means a downward component to the lateral gears, shafts and grinding elements during rotation of said central gear.

5. In a machine for grinding floors, a central gear having teeth inclined in an axial direction, a plurality of floating vertical shafts arranged around and radially spaced from said central gear and mounted for rotary movement, a lateral gear having correspondingly inclined teeth fixedly mounted on each shaft and meshing with the central gear, said shafts and their respective lateral gears being free at all times during operation to move up and down, a grinding element mounted on a lower end of each vertical shaft and supporting the latter shaft and the lateral gear mounted thereon, and driving means for moving the vertical shafts circumferentially around the central gear to cause the lateral gears, shafts and grinding elements to rotate, the incline of the teeth of the central and lateral gears being such as to impart a downward component to the lateral gears, shafts and grinding ele ments during the circumferential movement of said shafts.

6. A floor grinder comprising a carriage, Wheel means mounted on and supporting the carriage, a horizontal central gear mounted on the carriage and having teeth inclined in an axial direction, a plurality of floating vertical shafts arranged around and radially spaced from said central gear and mounted on the carriage for rotary movement, a lateral gear having correspondingly inclined teeth fixedly mounted on each shaft and meshing with the central gear, said shafts and their respective lateral gears being free at all times during operation to move up and down, a grinding element mounted on a lower end of each vertical shaft and supporting the latter shaft and the lateral gear mounted thereon, and driving means for causing the vertical shafts and the grinding elements thereof to rotate, the incline of the teeth of the central and lateral gears being such as to impart under the action of said driving means a downward component to the lateral gears, shafts and grinding elements during rotation of said shafts.

7. A floor grinder as claimed in claim 6 in which the central gear is wide enough to permit each lateral gear to move downwardly while continuing to mesh therewith a predetermined distance as the grinding element associated with each lateral gear wears away.

8. A floor grinder comprising a carriage, wheel means mounted on and supporting the carriage, a horizontal central gear mounted on the carriage and having teeth inclined in an axial direction, a plurality of floating vertical shafts arranged around and radially spaced from said central gear and mounted on the carriage for rotary movement, a lateral gear having correspondingly inclined teeth fixedly mounted on each shaft and meshing with the central gear, said shafts and their respective lateral gears being free at all times during operation to move up and down, a holder mounted on a lower end of each vertical shaft and adapted removably to hold a grinding stone projecting downwardly therefrom, said grinding stone supporting its holder, shaft and the lateral gear mounted on the latter, and driving means for causing the vertical shafts and holders to rotate, the incline of the teeth of the central and lateral gears being such as to impart under the action of said driving means a downward component to the lateral gears, shafts and holders during rotation of said shafts.

9. A floor grinder comprising a carriage, wheel means mounted on and supporting the carriage, a horizontal central gear mounted on the carriage and having teeth inclined in an axial direction, a plurality of floating vertical shafts arranged around and radially spaced from said central gear and mounted on the carriage for rotary movement, a lateral gear having correspondingly inclined teeth fixedly mounted on each shaft and meshing with the central gear, said shafts and their respective lateral gears being free at all times during operation to move up and down, a grinding element mounted on a lower end of each vertical shaft and supporting the latter shaft and the lateral gear mounted thereon, and power means on the carriage connected to the central gear to rotate the latter gear and thereby rotate the lateral gears, vertical shafts and grinding elements, the incline of the teeth of the central and lateral gears being such as to impart under the action of said driving means a downward component to the lateral gears, shafts and grinding elements during rotation of said central gear.

10. A floor grinder comprising a carriage, wheel means mounted on and supporting the carriage, a horizontal central gear mounted on the carriage and having teeth inclined in an axial direction, a plurality of floating vertical shafts arranged around and radially spaced from said central gear and mounted on the carriage for rotary movement, a lateral gear having correspondingly inclined teeth fixedly mounted on each shaft and meshing with the central gear, said shafts and their respective lateral gears being free at all times during operation to move up and down, a grinding element mounted on a lower end of each vertical shaft and supporting the latter shaft and the lateral gear mounted thereon, and driving means carried by the carriage for moving the vertical shafts circumferentially around the central gear to cause the lateral gears, shafts and grinding elements to rotate, the incline of the teeth of the central and lateral gears being such as to impart a downward component to the lateral gears, shafts and grinding elements during the circumferential movement of said shafts.

References Cited in the file of this patent UNITED STATES PATENTS 835,631 Mooney et a1. Nov. 13, 1906 862,747 Miller Aug. 6, 1907 1,694,738 Geary Dec. 11, 1928 2,171,060 De Spirt Aug. 29, 1937 2,289,117 Harrison July 7, 1942 2,300,138 Steele Oct. 27, 1942 2,680,260 Danielsson et a1. June 8, 1954 2,930,056 Loppin Mar. 29, 1960 FOREIGN PATENTS 217,856 Australia Feb. 7, 1957 OTHER REFERENCES Schottle et al., 1,091,302, printed Oct. 20, 1960, German application (Kl. 34c 5/04), 2 pp. spec., 1 sheet dwg. 

1. IN A MACHINE FOR GRINDING FLOORS, A CENTRAL GEAR HAVING TEETH INCLINED IN AN AXIAL DIRECTION, A PLURALITY OF FLOATING VERTICAL SHAFTS ARRANGED AROUND AND RADIALLY SPACED FROM SAID CENTRAL GEAR AND MOUNTED FOR ROTARY MOVEMENT, A LATERAL GEAR HAVING CORRESPONDINGLY INCLINED TEETH FIXEDLY MOUNTED ON EACH SHAFT AND MESHING WITH THE CENTRAL GEAR, SAID SHAFTS AND THEIR RESPECTIVE LATERAL GEARS BEING FREE AT ALL TIMES DURING OPERATION TO MOVE UP AND DOWN, A GRINDING ELEMENT MOUNTED ON A LOWER END OF EACH VERTICAL SHAFT AND SUPPORTING THE LATTER SHAFT AND THE LATERAL GEAR MOUNTED THEREON, AND DRIVING MEANS FOR CAUSING THE VERTICAL SHAFTS AND THE GRINDING ELEMENTS THEREOF TO ROTATE, THE INCLINE OF THE TEETH OF THE CENTRAL AND LATERAL GEARS BEING SUCH AS TO IMPART UNDER THE ACTION OF SAID DRIVING MEANS A DOWNWARD COMPONENT TO THE LATERAL GEARS, SHAFTS AND GRINDING ELEMENTS DURING ROTATION OF SAID SHAFTS. 